DAESH lost control of its last major Syrian stronghold yesterday as Iraqi forces also recaptured territory from the extremist group.

According to Syrian state-run TV, the army retook the key eastern city of Deir al-Zor on Friday, costing Daesh control of the country’s oil production centre.

Across the border, Iraqi forces say they have pushed the jihadists from the town of al-Qaim, also regaining control of the last border post held by the organisation.

The victories mark an important stage in the regional battle against Daesh, which had declared the land on either side of the official border a single province, using the area for the movement of arms, people and other assets.

The news came as aid agencies stepped up relief efforts in Syria as winter begins, with the UK announcing a new £62 million support package to cut child pneumonia deaths. International Development Secretary Priti Patel said: “Hundreds of thousands of vulnerable men, women and children face another deadly winter ahead.”

The Deir al-Zor operation was carried out as Syrian government forces press towards another key site on the River Euphrates — the town of Albu Kamal — supported by Russia and Iran.

In a statement, the Syrian military said: “The armed forces, in cooperation with allied forces, liberated the city of Deir al-Zor completely from the clutches of the Daesh terrorist organization.”

The terror group had been in control of most districts for three years, with hundreds of thousands of civilians affected.

However, the area has not yet been safe, with engineering units now working to identify improvised explosive devices, mines and other hazardous materials left behind as Daesh retreated.

Meanwhile, the recapture of al-Qaim means the network has lost around 95 per cent of its territory in Iraq, with more than 4.4m people now freed from its control, according to the American-led coalition there.

Although news of Daesh defeats is welcome, there are fears of future disputes over authority and territory due to the number of agents involved in the conflict. Syrian president Bashar al-Assad, who has been widely condemned for human rights abuses and the use of force and siege tactics in the battle to defeat armed revolutionaries, has strengthened his grip on power. Meanwhile, Kurdish peshmerga, both Shia and Sunni militias, Iranian fighters and other outfits have taken up arms against the group.

Millions of people displaced by the conflict remain in refugee camps, makeshift shelters and accommodation without proper heat or sanitation.

As November bites and temperatures drop below freezing, efforts are underway to prevent thousands of child deaths from pneumonia and other respiratory conditions.

One in three child deaths are caused by such illnesses, up from one in ten before the crisis began. Malnourishment and lack of hygiene make youngsters up to 15 times more likely to lose their lives to the conditions.

Working with Unicef, the World Health Organisation and other non-governmental organisations, the UK is to provide more than 1.3 million health care consultations, including 700,000 for children and women, as well as vaccinations for more than 100,000 people and winter kits of blankets and warm clothing for around the same number.

Meanwhile, 600 housing units will be fitted with doors, windows and heaters to give 3000 people a secure place to stay.

Patel said: “Pneumonia is an untold horror of the Syria crisis and helpless children are falling victim to the brutal assault of winter before their lives have properly begun. No child should die from the cold.

“I urge the international community to step up and provide support that will not only keep people alive but also give them a chance of rebuilding their lives.”